The standard ISO 14443 defines the requirements for a radio frequency transaction between a wireless smart card and a terminal.
The transaction comprises a plurality of successive phases. During a first phase, known as switching on, the radio frequency interface of the terminal is switched on and reinitialised. The terminal transmits with a 13.56 MHz carrier. The cards located in the transmission field rectify the carrier transmitted in order to supply their circuits.
During a second phase, known as startup and anti-collision phase, the terminal determines the presence of one or more cards in its transmission field. According to ISO 14443-3 type B, the terminal transmits in particular a request requiring that the cards located in its transmission field present themselves and defining a number of response time slots. The terminal also defines the response time slots, the end of transmission of the request launching the first time slot. FIG. 1 illustrates said operation: the REQB4SM request of the terminal announces 4 response time slots for the various cards in its transmission field. The first time slot starts at the end of the REQB4SM request. The terminal then transmits SM2, SM3 and SM4 slot markers the end of which marks the start of the second, third and fourth time slots.
Two cards respond to the REQB4SM request. The cards respond respectively via the ATQB1 and ATQB2 response frames. Each card responds in a distinctive time slot via a single response frame. An ATQB response comprises the following data: a pseudo-random card identifier for the communication parameters and information for the execution of an application by default. The information comprises in particular an identifier of the single application group (designated by the AFI acronym in English) by default in the card. The information also comprises the number of loaded applications associated with this application group along with the total number of applications loaded in the card. The terminal thus determines the characteristics of said cards and selects one or more.
During a third phase, known as activity phase, command exchanges are performed between the terminal and a selected card to enable execution of an application group (transport, bank operation, counting of loyalty points, identity check, etc.) during the transaction.
More and more frequently, a smart card has a plurality of distinctive applications, application groups or sub-groups. In order to declare said various applications or application groups, a known method proposes carrying out a plurality of successive startup and anti-collision phases. At each new phase, the identifier of the single application group by default is associated with another application or application group.
Said method has disadvantages. Some transactions, such as the authorisation of passage of a user at a tube portico or toll, require a total execution time less than 100 milliseconds. The duration (and thus the number) of startup and anti-collision phases must therefore be limited. Thus, all of the applications or application groups cannot be declared in such a transaction.